Numerous studies have demonstrated that only a small percentage of subjects with ocular hypertension actually develop primary open-angle glaucoma. Efforts to identify specific single factors as prognostic indicators of glaucomatous visual field loss have been unrewarding. In a previous retrospective study using a system of multivariate analysis, it was possible to identify accurately those individuals who developed glaucoma among a group of subjects with ocular hypertension. The present study is designed as a prospective evaluation of this multivariate estimate of risk in a selected population of subjects with ocular hypertension. Using the above system, estimates of the probability of visual field loss will be calculated for each subject at the beginning of the study. All subjects will then be followed for five years, following which the predictive estimates of visual field loss will be evaluated.